This invention relates to a liquid crystal composition and more particularly to a liquid crystal composition for use in a liquid crystal light valve which operates in optical ON-OFF control in response to signals applied to the liquid crystal composition sealed in a liquid crystal panel, the signals being of a lower frequency f.sub.l and a higher frequency f.sub.h than the crossing or critical frequency f.sub.c wherein the dielectric anisotropy of the liquid crystal is 0. The invention also relates to a liquid crystal light valve including the novel liquid crystal composition having high-speed response characteristics which permit the liquid crystal panel to respond optically at high speeds.
In recent years, information processing techniques have made remarkable progress to the point where large amounts of information are processed at high speeds. Office automation equipment has become widely popularized. In view of these advancing techniques, the printer utilized as an output of a computer must function at high speed and provide a high quality level of printing at modest cost. Unfortunately, printers which satisfy these requirements are not generally available in spite of the strong demand for these products. Presently, an electro-photographic printer in which a liquid crystal light valve is positioned at a light signal generator meets some of the above-mentioned requirements on a practical level and is of interest in the field. Such a printer is disclosed in Japanese Laid-Open Patent Publication No. 81-93,568.
A laser printer which utilizes electro-photographic technology is also presently in use as a non-impact printing method. The preferred properties of such a printer, such as high quality printing and high printing speed are achieved by printers of this kind. However, due to their large size and complexity, these printers necessarily suffer from high manufacturing cost. Accordingly, an inexpensive printer of high quality is desired as an output and such printers utilizing liquid crystal light valves are under consideration.
While liquid crystal compositions for use in liquid crystal display devices have been thoroughly researched and developed, it has been found that those compositions are less than completely satisfactory for a liquid crystal light valve. The conventional liquid crystal compositions are not suitable for use in a liquid crystal light valve with respect to, for example the driving voltage, the liquid crystal phase temperature and reliability.
Accordingly, it is desirable to provide a liquid crystal composition suitable for use in a liquid crystal light valve in an electro-photographic printer having improved response speed, does not exhibit temperature dependency and is highly reliable.